Stern tube construction



Jan. 8, 1963 J. BROWN 3,07 4

STERN TUBE CONSTRUCTION Filed Dec. 9, 1960 fie. 1

mmvron JAMES BROWN BY Mn, i

* ATTORNEYS United States Patent Chico 3,072,447 STERN TUBE CONSTRUCTION James Brown, Lakewood, Ohio, assignor to The American Ship Building Company, Cleveland, Ohio, a corporation of New Jersey Filed Dec. 9, W60, Ser. No. 74,877 7 Claims. (Cl. 308-46) This invention relates to freeze damage prevention in marine vessels and, more particularly, with respect to the stern tube through which the propeller shaft extends. An object of the invention is to provide a novel stern tube construction affording freeze damage protection without need for any subsequent attention or periodic servicing.

Many marine vessels operating in northern regions, such as in the Great Lakes area, are placed in an inactive or laid-up status during winter months. To place a vessel in such an inactive status it has heretofore been necessary to remove water from the stern tube toprevent disruptive damage thereto by freezing of the water therein.

Since the stern tube is on a normally water-submerged portion of the hull, the water cannot ordinarily be removed therefrom by gravity drainage. It has accordingly been the practice heretofore to expel the Water from the stern tube by forcing a displacement medium thereinto. The displacement medium so employed has usually been heavy oil, an oil and tallow mixture, or other such nonmiscible liquid.

The use of these displacement medii involves considerable expense and the removal thereof presents a further problem when the vessel is to be restored to active service. Such removal usually requires steaming to reduce the viscosity of the medium so that it can be pumped or flushed out. The displacement material removed from the stern tube frequently also causes contamination of harbor waters.

The present invention eliminates these problems and disadvantages by providing a novel stern tube construction embodying freeze damage preventing means which does not require the use of any such expendible displacement medium but remains in its installed location and is continuously effective without requiring periodic servicing.

This invention further provides novel freeze damage resistant construction for a marine vessel comprising a stern tube on a normally water-submerged portion of the hull and containing flexible means exposed to the water present in such stern tube so as to be subject to compressive flexure by the thrust of ice formation within the tube.

The invention also provides a novel freeze damage protected stern tube of the character above indicated wherein the flexible means is substantially nonabsorbent and contains void spaces, as for example, a set unicellular plastic material.

Additionally, this invention provides a novel stern tube of the character above indicated comprising a tubular housing having axially adjacent annular bearing members therein, usually water-lubricated bearing members, andwherein the flexible material comprises a sleeve in a coaxial relation between the bearing members.

Other novel characteristics, objects and advantages of this invention will be apparent in the following detailed description and in the accompanying drawing forming a part of this specification and in which,

FIG. 1 is a partial side elevation of a marine vessel equipped with the novel freeze damage resistant stern tube of this invention;

FIG. 2 is a longitudinal section on a larger scale taken through the novel stern tube, as indicated by section line 2-2 of FIG. 1; and

FIG. 3 is a transverse section of the stern tube taken on section line 33 of FIG. 2.

3,072,447 Patented Jan. 8, 1963 The accompanying drawing illustrates a preferred and highly practical embodiment of the freeze damage resistant stern tube 10 of this invention and, as such, shows the stern tube located on a normally water-submerged portion of the hull 11 of a marine vessel.

The hull 11 includes a stern frame 12 which supports a swingable rudder 13 and has a hollow boss 14 in which the after end of the stern tube 16 is received and supported. A propeller shaft 15 extends through, and is rotatably supported in, the stern tube 10 and drives a propeller 16 which is fixed on the after end of such shaft. A rope guard 17, in the form of an annular sleeve here shown attached to the boss 14, is disposed in a surrounding relation to the propeller shaft and extends into adjacently spaced relation to the hub of the propeller 16.

The stern tube 10 comprises a tubular housing 20 and bearing means therein for rotatably supporting the propeller shaft 15 and, in this case, comprising axially spaced bearing members 21 and 22. The tubular housing 20 in cludes reduced portions 23* and 23 which are engaged in bores 24 and 24 of the stern frame boss 14.

The bearing members 21 and 22 are of a conventional form comprising bearing sleeves 26 and 27 received in bores of the tubular housing 20 as retainer members, and axially adjacent annular groups of bearing elements 28 and 29 held by the bearing sleeves. The bearing elements 28 and 29 comprise bearing blocks of suitable material, usually a nonmetallic material such as lignumvitae wood.

The stern tube It has passage means therein for a flow of water axially through the housing '20 in a cooling and lubricating relation to the bearing members 21 and 22. The passage means for this purpose is formed in part by the radial running clearance between the propeller shaft 15 and the bearing members 21 and 22, and in part by the intervening annular space 30 contained in the housing between the'adjacent ends of the sleeves 26 and 27.

The bearing sleeves 26 and 27 are of a suitable shape to receive and hold the annular groups of bearing blocks 23 and 29. The sleeve 26 is provided at the forward end thereof with an annular flange 32 to which a cover ring 33 is suitably attached. The cover ring 33 contains an annular chamber 34 to which the supply of cooling and lubricating water is delivered under pressure through a conduit 35 for feeding to the bearing member 21. The Water thus supplied to the bearing member 28 cools and lubricates the same and, after traversing the space 30, passes through the bearing member 22 to cool and lubricate it also.

The sleeve 27 of the bearing member 22 preferably projects from the stern frame boss 14 into the annular space enclosed by the rope guard 17, as shown in FIG. 2. A

' threaded portion on the after end of the tubular housing 20 likewise projects from the stern frame boss 14 and is engaged by a nut 35 in clamping co-operation with the boss for retaining the stern tube 10 in an assembled relation therein. The cooling and lubricating water which traverses the bearing member 22 is discharged from the after end thereof into the space within the rope guard 17.

reeze damage preventing means provided in the stern tube 10 comprises flexible means 37 located in the tubular housing 20,'in an exposed relation to the water which has been supplied thereto or is present therein, so as to be subject to compression flexure by the thrust of ice formation Within the stern tube. The flexible means 37 is here shown in the form of a sleeve 38 surrounding the shaft' 15 and received in a channel-shaped internal annular recess 39 of the tubular housing 20 so as to be located in the tubular housing at a point intermediate the bearing members 21 and 22, that is, in the portion of the passage means which is formed by the'annular space The flexible means 37 can be any suitable material having sufficient flexibility to absorb the thrust of the ice formation within the stern tube and to restore itself to its initial condition when the ice melts. The material comprising the flexible means 37 should be substantially nonabsorbent in character so as not to be permeated by the water in the stern tube and preferably has void spaces providing pockets in a noncommunicating relation therein to increase the flexibility of the material without increasing the tendency of the material to absorb water. The flexible means 37 may, for example, comprise set unicellular plastic material such as polyvinyl chloride or other suitable plastic.

Since the flexible means 37 is contained in the tubular housing 29 of the stern tube 10 in an exposed relation to the water in the passage means of the stern tube, it will be subject to compression by the thrust of ice formation within the tube and will effectively prevent such thrust from damaging the stern tube or the bearing members 21 and 22 thereof. The flexible means 37 will remain permanently in place and continuously effective and will eliminate the need for removing water from the stern tube It) as has heretofore been necessary. Since the flexible means 37 is not ordinarily subject to deterioration it will not require periodic inspection or replacement.

From the accompanying drawing and the foregoing detailed description it will accordingly be recognized that this invention has provided a novel stern tube construction for marine vessels which is highly resistant to freeze damage and which is very useful, economical and practical by reason of the achievement of the various important advantages already explained hereinabove.

Although the novel stern tube construction of this invention has been illustrated and described herein to a somewhat detailed extent it will be understood, of course, that the invention is not to be regarded as being correspondingly limited in scope but includes all changes and modifications coming within the terms of the claims hereof.

Having described my invention, I claim:

1. A freeze-damage-prote'cted structure comprising marine vessel means including a stern tube housing having an axial bore adapted to accommodate a propeller shaft; axially spaced bearings in said housing for rotatably supporting said shaft therein; portions of said housing located between said bearings being of a transverse dimension in relation to the transverse dimension of said shaft to provide an intervening annular space as a combined expansion chamber and flow passage for water as a coolant and lubricant for said bearings; and flexible means in said chamber and subject to compressive flexure by the expansive thrust of ice formation in said chamber.

2. A freeze-damage-protected structure as defined in claim 1 wherein said flexible means comprises a body of substantially nonabsorbent material having void pockets in a distributed and substantially noncommunicating relation therein.

3. A freeze-damage-protected structure as defined in claim 1 wherein said flexible means comprises a body of et unicellular plastic material.

4. A freeze-damage-protected structure as defined in claim 1 wherein said flexible means comprises a sleeve of set unicellular plastic material.

5. A freeze-damage-protected structure comprising marine vessel means of the kind ordinarily remaining afloat during the winter season including a stern tube housing in a normally water-submerged location thereon and having an axial bore adapted to accommodate a propeller shaft; bearing means in said housing at the rear end thereof for rotatably supporting said shaft; water supply means connected with said housing at the forward end thereof; said bore being of a diameter in relation to the diameter of said shaft to provide therebetween an intervening annular space for a flow of Water from said supply means to said bearing means for cooling and lubricating the latter; and flexible means of a substantially nonabsorbent character in said housing intermediate said bearing means and said supply means and being in contact with the water in said space and subject to compressive flexure by ice formation due to freezing of Water in said space.

6. A freeze-damage-protected structure comprising marine vessel means including a stern tube housing in a normally water-submerged location thereon and having an axial bore adapted toaccommodate a propeller shaft; bearing means in said housing for rotatably supporting said shaft; said bore being of a diameter in relation to the diameter of said shaft to provide therebetween an intervening space for water in a cooling and lubricating relation to said bearing means; and flexible means of a substantially nonabsorbent character in said housing in contact with the water in said space and being subject to compressive flexure by ice formation in said space; said bearing means comprising axially adjacent annular groups of nonmetallic blocks, and said flexible means comprising coaxial sleeve means disposed between certain of said groups.

7. A freeze-damage-protected structure comprising marine vessel means including a stern tube housing in a normally water-submerged location thereon and having an axial bore adapted. to accommodate a propeller shaft; bearing means in said housing for rotatably supporting said shaft; said bore being of a diameter in relation to the diameter of said shaft to provide therebetween an intervening space for water in a cooling and lubricating relation to said bearing means; and flexible means of a substantially nonabsorbent character in said housing in contact with the water in said space and being subject to compressive flexure by ice formation in said space; said housing having an internal annular channel extending around, and in communication with, said bore and said flexible means comprising set unicellular plastic material disposed in said channel.

References Cited in the file of this patent UNITED STATES PATENTS 676,889 Gasparini June 25, 1901 931,112 Ballard Aug. 17, 1909 2,306,664 Scott-Paine Dec. 29, 1942 2,600,103 Peck June 10, 1952 

1. A FREEZE-DAMAGE-PROTECTED STRUCTURE COMPRISING MARINE VESSEL MEANS INCLUDING A STERN TUBE HOUSING HAVING AN AXIAL BORE ADAPTED TO ACCOMMODATE A PROPELLER SHAFT; AXIALLY SPACED BEARINGS IN SAID HOUSING FOR ROTATABLY SUPPORTING SAID SHAFT THEREIN; PORTIONS OF SAID HOUSING LOCATED BETWEEN SAID BEARINGS BEING OF A TRANSVERSE DIMENSION IN RELATION TO THE TRANSVERSE DIMENSION OF SAID SHAFT TO PROVIDE AN INTERVENING ANNULAR SPACE AS A COMBINED EXPANSION CHAMBER AND FLOW PASSAGE FOR WATER AS A COOLANT AND LUBRICANT FOR SAID BEARINGS; AND FLEXIBLE MEANS IN SAID CHAMBER AND SUBJECT TO COMPRESSIVE FLEXURE BY THE EXPANSIVE THRUST OF ICE FORMATION IN SAID CHAMBER. 